The present invention relates to the removal of embolic debris from blood vessels, and particularly at locations which cannot be safely reached by surgical techniques.
It is known that severe medical conditions can be caused by the formation, in blood vessels, of plaque or thrombi which frequently narrow the blood flow passage in a vessel to an extent which places an undue burden on the heart or severely limits the ability to supply blood to various organs.
While a number of techniques for dealing with this problem have been proposed, many of these techniques are surgical in nature in that they require direct access to the site of such obstruction. In many cases, this is not medically possible. A significant example is cerebral blood vessels which cannot be safely exposed by surgical techniques.
Recent years have seen the introduction of less invasive techniques in which obstruction removal devices are introduced into a blood vessel at a point which is close to the surface of the skin and are then moved along the blood vessel to the site of an obstruction. Such devices employ lasers, rotoblades, or ultrasound, for example.
The use of such procedures leads to the creation of debris constituted by small particles of the plaque or thrombus and, in the absence of special measures, these particles will be carried along in the blood flow. Particularly in small vessels, such as cerebral vessels, these particles can cause damage to organs downstream of the obstruction.
While suction may be used concurrently with the obstruction removal operation, this will not always effect complete withdrawal before some debris particles or emboli have moved out of the suction region.
Catheters are known in the art which are equipped with blood vessel blocking balloons and which are employed for various purposes, including balloon angioplasty (U.S. Pat. No. 4,581,017) and control of direction of blood flow (U.S. Pat. No. 4,592,340). It appears to be the universal practice to provide balloons which inflate symmetrically around the catheter in order to center the catheter in the blood vessel.